| 1. |
- Oliveira, Helena Rodrigues, et al.
(författare)
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Biogas potential of biowaste: A case study in the state of Rio de Janeiro, Brazil
- 2024
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Ingår i: Renewable energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0960-1481 .- 1879-0682. ; 221
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion has been widely applied for waste treatment, renewable energy generation , biofertilizer production. The biogas potential in Brazil is sizable, but the state of Rio de Janeiro is largely dependent on fossil fuels , there is a lack of biogas potential assessments in the state. Thus, this study evaluated biomethane, electricity and biofertilizer potentials in the region. Three different scenarios of biomass supply were considered for four major biowaste streams: sewage sludge; cattle manure; sugarcane processing waste; and food waste. Biomethane generation from the assessed sources could reach 0.6-1.3 billion Nm(3) year(-1), corresponding to 1,768-3,961 GWh year(-1) of electricity , 1.6-3.3 million Mg year- 1 of biofertilizer. Cattle manure was responsible for 73-84% of the projected biomethane production, presenting an opportunity to reduce the sig-nificant emissions from livestock farming. The estimated biofertilizer production could meet the demands of the state , the produced electricity could offset up to 10% of the demand. The gas grid could facilitate the dis-tribution of upgraded biomethane, and 10-22% of the natural gas demand could be met. The findings of this work highlight the high potential for biogas generation in Rio de Janeiro, which is up to seven times larger than the current production.
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| 2. |
- Rodrigues Oliveira, Helena, et al.
(författare)
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A novel approach to estimate methanogenic pathways in biogas reactors via stable carbon isotope analysis
- 2024
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Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 183
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Tidskriftsartikel (refereegranskat)abstract
- Two microbial pathways are responsible for most of the methane produced during anaerobic digestion: acetoclastic methanogenesis (AM) and hydrogenotrophic methanogenesis (HM) coupled with syntrophic acetate oxidation (SAO). Identifying the dominant methanogenic pathway active in a system provides the information necessary to manage and optimize productivity, stability, process control, and gas quality in biogas reactors. In this study, a modified method is proposed to estimate methanogenic pathways in different biogas systems via short-term parallel incubations with methyl-labeled acetate (2-13C-acetate). Cavity ring-down spectroscopy was applied to measure the δ13C–CH4 and δ13C–CO2 isotopic signatures of produced biogas. Preliminary experiments demonstrated that longer incubation times led to significant variations in δ13C–CH4 and δ13C–CO2 and consequently interfered with the calculated fraction of CH4 produced from HM (fHM). This variability is likely caused by the dilution of 13CH4 and 13CO2 as 2-13C-acetate is consumed, along with potential changes in organic matter quality and quantity, microbial community composition, and environmental factors such as pH, volatile fatty acid content, and ammonia levels, during longer incubations. We applied this new approach to sludge from six full-scale reactors (three mesophilic and three thermophilic) and validated its potential with consistent estimates of fHM with minimal variation. Mesophilic reactors exhibited AM dominance, while HM was the dominant pathway in thermophilic reactors, aligning with reports in the literature.
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